Ammunition and explosives – Jacketed or cartridge gas generator
Reexamination Certificate
1999-05-18
2001-11-13
Tudor, Harold J. (Department: 3641)
Ammunition and explosives
Jacketed or cartridge gas generator
C280S741000
Reexamination Certificate
active
06314888
ABSTRACT:
TECHNICAL FIELD
The invention relates to a multi-stage gas generator.
BACKGROUND OF THE INVENTION
Multi-stage gas generators with propellant charges which are able to be ignited independently of each other can generate different quantities of gas, coordinated with vehicle occupants or accident-specific parameters. If only one propellant charge is ignited, the outflowing hot gas automatically heats the outer and inner walls, however, so that heat is passed on to the non-ignited propellant charge. Theoretically, this can lead to the non-ignited propellant charge igniting itself after a few minutes, owing to the relatively slow heat transport. This involves dangers both for the occupant who is still to be found in the vehicle and also for rescue personnel.
BRIEF SUMMARY OF THE INVENTION
The invention provides a multi-stage gas generator, in which this danger can be largely ruled out. The multi-stage gas generator according to the invention comprises a housing with an outer wall and also inner walls, at least two combustion chambers filled with at least one propellant charge, one igniter associated with each propellant charge for the independent activation of each propellant charge, and at least one thermal insulation arrangement between the propellant charges. The arrangement reduces a transport of thermal energy, generated on the ignition of a propellant charge, to the other non-ignited propellant charge to such a high extent that the non-ignited propellant charge remains below its autogenous ignition temperature. Instead of or additionally to the thermal arrangement a cooling arrangement may be provided.
The first solution makes provision that at least one thermal insulation arrangement is provided between the propellant charges. This thermal insulation arrangement reduces the transportation of thermal energy, generated on ignition of one of propellant charges, to another non-ignited propellant charge to such a high extent that the non-ignited propellant charge remains below its autogenous-ignition temperature.
The second solution according to the invention makes provision for at least one cooling arrangement in the region of at least one of the propellant charges. The cooling arrangement thereby uncouples the thermal flow from one ignited propellant charge to another.
According to a development of the invention, the combustion chamber is delimited by a combustion chamber wall. The thermal insulation arrangement consists of an insulating wall which on the inner face covers or lines at least sections or even the entire combustion chamber wall. The insulating wall is of insulating material, preferably plastic, such as polyamide or polyvinylchloride having a low thermal conductivity. Furthermore, ceramic can also be used as insulating material.
Preferably the gas generator is a tubular gas generator with two combustion chambers arranged at opposite ends of the tube and with at least one filter chamber arranged between the combustion chambers. According to the preferred embodiment, each combustion chamber has its own filter chamber, the filter chambers being arranged between the combustion chambers. Between the filter chambers, in turn, the thermal insulation arrangement is provided, by which the filter chambers are spaced apart from each other. In this intermediate space between the filter chambers, insulating material or gas, such as air for example, can provide for an appreciable thermal uncoupling of the filter chambers and hence of the two halves of the gas generator. Furthermore, a vacuum provided between the filter chambers can also provide for such a thermal uncoupling.
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Muller Werner
Schropp Roland
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Airbag Systems GmbH & Co. KG
Tudor Harold J.
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